题解 | #返回每个顾客不同订单的总金额#
返回每个顾客不同订单的总金额
http://www.nowcoder.com/practice/ce313253a81c4947b20e801cd4da7894
先子查询，得到每个订单的总金额 再与orders表连接，得到每个顾客的不同订单的总金额
select cust_id,sum(a)
from Ordersjoin
(select order_num,sum(item_price*quantity) as a
from OrderItems
group by order_num) as b
on Orders.order_num = b.order_num
group by cust_id
order by sum(a) desc
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